The present disclosure relates to the field of power tools used for interior finishing applications in new or modified building construction, and especially to the process of finishing expansive foam insulation installed in vertical walls. A typical wall construction includes a first and a second wall material such as wall-board or gypsum-board installed on opposite sides of vertical studs. After the first wall is mounted on one side of the studs, the foam insulation is painted on the interior surface of the first wall and allowed to expand. The insulation expands away from the first wall and beyond where the second wall is intended to be positioned. This is necessary to insure that no void is left within the wall when the second wall is mounted on the studs. It is necessary to shave, cut, plane or dress the protruding surface of the insulation material so that it is very nearly even (coplanar) with the open stud faces that will receive the second wall. Typically, some of the expanded foam will coat the open stud faces as well and this overflow insulation must be removed so that the second wall can sit flush on the studs. Tools designed for trimming the insulation are in common use and may be used for other applications where the dressing of soft materials is called for. Tools currently in use specifically for trimming expanding foam insulation are manufactured by Spray Foam Equipment, an Internet company, by APF, LLC of Allendale, Mich., and by Krendal Machine Company of Delphos, Ohio.